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通过对明代固原地区历史资料的搜集、整理、分析,对其干旱灾害等级化及成因等问题进行了研究。结果表明,固原地区自1368年到1644年间的277a中,共发生干旱灾害118次,平均每2.35a发生1次;其中轻度旱灾20次,占旱灾总数的16.9%;中度旱灾38次,占旱灾总数的32.3%;大旱灾42次,占旱灾总数的35.6%;特大旱灾18次,占旱灾总数的15.2%。该地区旱灾可分为4个阶段:第1阶段的1368—1424年和第3阶段的1505—1604年是旱灾的低发期;第2阶段的1425—1504年和第4阶段的1605—1644年是旱灾的高发期。该地区旱灾的季节性特征是单季旱占55.9%,其中夏旱所占比重最高,春旱、秋旱次之,冬旱较为稀少;季节性连旱占44.1%,其中春夏连旱和春夏秋3季连旱分别高达17.8%、15.3%。该地区明代处于气候的干冷期,年降水量减少是发生旱灾的主要原因。固原地区具有指示该时代气候变化特征的5次干旱气候事件,分别是明代的1437—1442年、1481—1490年、1608—1617年、1627—1634年、1637—1641年。
Through the collection, collation and analysis of the historical data in the Guyuan area in the Ming Dynasty, this paper studied the grading and causes of drought disaster. The results showed that there were 118 drought disasters in 277a from 1368 to 1644 in Guyuan area, with an average of 2.35a once. Among them, mild drought was 20 times, accounting for 16.9% of the total number of drought; moderate drought was 38 times, Accounting for 32.3% of the total number of droughts; 42 large droughts, accounting for 35.6% of the total number of droughts; 18 especially severe droughts, accounting for 15.2% of the total number of droughts. Drought in the region can be divided into four phases: the first phase of 1368-1424 and the third phase of 1505-1604 are the low season of drought; the second phase of 1425-1504 and the fourth phase of 1605-1644 Year is the high incidence of drought. Seasonal seasonal drought is 55.9% in single season, of which summer drought accounts for the highest proportion, followed by spring drought and autumn drought, and scarce winter drought. Seasonal drought accounts for 44.1% Spring, summer and autumn, even the drought in the third quarter up to 17.8%, 15.3%. The Ming Dynasty in the dry and cold climate, the annual decrease in precipitation is the main cause of drought. The Guyuan area has five arid climate events indicating the characteristics of climate change in the era, which are respectively from 1437 to 1442, from 1481 to 1490, from 1608 to 1617, from 1627 to 1634 and from 1637 to 1641 in the Ming Dynasty.